Hot delivery and hot charging is effective measure of energy saving and consumption reducing in iron and steel industry. However, surface cracks of
steel plates produced by HCR can be found easily and frequently, which may
be improved through rapid cooling of slab’s surface before HCR. It has been obtained that slabs microstructure such as fine ferrite-pearlite, granular bainite, upper bainite, lower bainite, martensite, through different
cooling conditions. After that, slabs were reheated to 1200℃. All specimens’ properties were analysed through tensile test, optical microscope, SEM, and TEM. The results show that, combination property of lower bainite is the best: the crystal particles were fine and even, the precipitate of V and Nb Microalloy was relatively small amount and even, the strength is high, the plasticity is good. Surface crack of lower bainite specimen was not found after reheating.